As large-scale integrated (LSI) semiconductor circuit devices further advance in miniaturization, a need arises for an ultra-thin dielectric film capable of offering enhanced electrical insulation performances. In prior known LSI chips, a film of silicon oxide (SiOx, where the suffix “x” is usually 2) has been widely used as a multi-purpose insulative film. However, in near future, it becomes inevitable to use several dielectric film materials in a way pursuant to respective on-chip circuit element functions in such LSI devices.
Dielectric films for use in the currently available ultralarge-scale integrated (ULSI) circuit chips include a gate insulating film of metal oxide semiconductor field effect transistors (MOSFETs), an insulator film between floating and control gates of a memory cell transistor in electrically erasable programmable nonvolatile semiconductor memory devices—for example, “Flash” memory of the floating gate type, an insulator film between charge trapping film and control gates of a memory cell transistor in electrically erasable programmable nonvolatile semiconductor memory devices—for example, “Flash” memory of the MONOS (metal oxide nitride oxide silicon) type, and a tunneling insulator film of a memory cell transistor in electrically erasable programmable nonvolatile semiconductor memory devices—for example, “Flash” memory of floating gate type or MONOS type or others. These dielectric films are generally required to have high dielectric constant (high-k) and low leakage current. A promising one of such dielectric films is a lanthanoid aluminate film, e.g., a lanthanum aluminate (LaAlO3) film.
For fabrication of the lanthanoid aluminate film, studies have traditionally been made to employ pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) or molecular beam deposition (MBD) methods. These film fabrication methods are inherently research-use processes, which are for preparing small-size samples slowly and carefully at increased costs. Thus, it does not appear that this approach is well adaptable for use in mass-production of the film. From a viewpoint of industrial applications, it is desirable to use sputtering techniques. This can be said because the sputtering is readily applicable to the manufacture of large-size workpieces at low costs while reducing complexities in process designs.
A sputtering method of forming a high-k dielectric film, e.g., silicate film, for use in ULSI devices is disclosed in JP-A 2003-234471(KOKAI). A ferroelectric film manufacturing method is found in JP-A 2003-224123(KOKAI).